Wait, check this out.
Charvaka flips through the alphabet book and stops at a page.

U for Unilateralis Cordyceps,
The fungus enters an ant's body through its respiration. It invades it's brain and changes how it perceives smell, because ants do everything they do from their smell of pheromones, right? So this microscopic little fungal spore then makes the ant climb up the stem of a plant and bite hard on a leaf, with an abnormal force.
The fungus then kills the ant, and continues to grow, leaving the ant's exoskeleton intact. So, a small fungus drives an ant around as a vehicle, uses it as food and shelter and then as the ultimate monument to itself.
And when the fungus is ready to reproduce, its fruiting bodies grow from the ant's head and rupture, releasing the spores, letting the wind carry them to more unsuspecting food.

There. Our entire idea of free will down the bin. One single small fungus spore does that to an ant.
You have trillions of bacteria in your body. How do you know where you end, and where your environment begins?